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United States Department of Agriculture

Agricultural Research Service

2010 Annual Report

1a.Objectives (from AD-416)
Develop improved rubber composites and their applications by using bio-based fillers. The research product of this work will aid in generating new markets for agricultural materials, and alleviate the problem of surplus agricultural commodities. This work will also aid in reducing our dependence on petroleum by substituting bio-based fillers from renewable resources for petroleum-based fillers (carbon black).

1b.Approach (from AD-416)
This proposal seeks to develop various economically viable bio-based fillers for rubber composite applications, and their optimum use and processing technology in rubber applications. The proposed experimental approach will investigate factors that can influence the properties of rubber composites such as filler size, filler structure, filler-filler interactions, and filler-rubber interactions. The results will then be used to identify commercially viable bio-fillers and to optimize the composite properties. The proposed experiments will also investigate the mixing and flow behaviors of bio-filler reinforced rubber composites, and develop a commercially viable processing technology for these composites.

3.Progress Report
The goal of this project is to substitute petroleum-based fillers (carbon black) with bio-based fillers from renewable resources to contribute to our material sustainability. In the current development, effects of corn flour treatments, combination of corn flour with biochar fillers, and processing methods of corn flour on the polymer composite properties were investigated and evaluated for their potential in composite applications. The composites reinforced by untreated corn flour and gelatinized/shear-degraded corn flour were prepared by a melt process with an internal mixer and compression-molded to investigate their mechanical properties. The results showed that the composites prepared by this method had moduli less than those prepared by a freeze-drying method, but had higher elongation and toughness. The research indicates that a further improvement of the composite properties may require better bonding between bio-filler and polymer matrices. A processing method with an internal mixer was also applied to defatted soy flour reinforced rubber composites. The results showed a great potential to produce useful rubber composites with an economical process. Evaluation of cornstarch-biochar filled rubber composites. Cornstarch has shown excellent reinforcement properties when used as a filler in styrene-butadiene rubber (SBR) latex, but these composites have poor fatigue and recovery properties; they are typically very brittle compared to control samples made with carbon black. To address this, rubber composites were formulated using a blend of cornstarch and pulverized renewable biochar. Unmodified biochar has weaker reinforcement properties than cornstarch but much better fatigue and recovery properties; it also has the added advantage of not competing with the food industry. Rubber composites made with equal parts cornstarch and biochar had much better fatigue properties (by nearly a factor of.
2)than cornstarch and better reinforcement properties than the carbon black controls at filler concentrations up to 30%. Future studies on biochar surface chemistry and improved selection of biochar feedstocks should improve upon these results even further. In order to significantly improve reinforcement properties of corn flour at lower filler concentrations for making rigid composites, another study was conducted with heat-treated corn flour in the formulation of rubber composites. Another category of bio-fillers under development for rubber reinforcement involved prototype nanoparticles produced by attaching a degradable synthetic polymer to seed protein molecules. These nanoparticles strongly adhered onto the surface of hydrophobic materials. The developed nanoparticles will be used as filler for the fabrication of nanocomposites. The characteristics of these nano-fillers also allow them to be miscible with a wide range of rubber materials. The current progress contributes to the development of economical and renewable reinforcement fillers for polymer composite applications and has potential scientific and industrial impact for developers of polymer composites.

1. Rubber reinforcement with modified corn flour. To contribute to the sustainability of materials we use today, development of different economical alternatives is required. PPL Unit scientist at National Center for Agricultural Utilization Research in Peoria,IL, developed a method using gelatinized and shear-degraded corn flour mixed with rubber emulsion and then melt-processed. The resulting material has better mechanical properties for rubber applications than untreated corn flour. This accomplishment will impact the technology of rubber composite applications by providing reinforcing fillers based on renewable agricultural materials instead of petroleum/natural gas derived fillers.

2. Rubber reinforcement with corn starch/biochar. To optimize the economical value and application properties of bio-fillers, PPL Unit scientist at National Center for Agricultural Utilization Research in Peoria,IL, used corn starch and biochar together as co-fillers to enhance the mechanical properties of the rubber material. The resulting rubber composites with a certain ratio of starch/biochar have some mechanical properties that are comparable to those of carbon black-filled composites. This accomplishment will impact the technology of rubber composite applications by providing reinforcing fillers based on renewable agricultural materials instead of petroleum/natural gas derived fillers.

Review Publications
Jong, L. 2009. Effect of Hydrolyzed Wheat Gluten and Starch Ratio on the Viscoelastic Properties of Rubber Composites. Journal of Applied Polymer Science. 114(4):2280-2290.

Liu, S.X., Kim, J. 2009. Study of Asorption Kinetics of Surfactants onto Polyethersulfone Membrane Surface Using QCM-D. Desalination. 247(1):355-361.

Kim, S., Xu, J., Liu, S.X. 2010. Production of Biopolymer Composites by Particle Bonding. Composites Part A. 41:146-153.

Last Modified: 10/8/2015
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